When I break a block near the turret, minecraft crashes.
It would also not be bad if you had somewhere written about how many turrets can be put on the base.

---- Minecraft Crash Report ----

WARNING: coremods are present:
Contact their authors BEFORE contacting forge

// Surprise! Haha. Well, this is awkward.

Time: 2/4/19 8:36 PM
Description: Tesselating block model

java.lang.NullPointerException: Tesselating block model
at omtteam.openmodularturrets.blocks.BlockTurretBase.func_149751_l(BlockTurretBase.java:151)
at net.minecraft.block.state.BlockStateContainer$StateImplementation.func_185895_e(BlockStateContainer.java:327)
at net.minecraft.client.renderer.BlockModelRenderer$AmbientOcclusionFace.func_187491_a(BlockModelRenderer.java:660)
at net.minecraft.client.renderer.BlockModelRenderer.renderQuadsSmooth(BlockModelRenderer.java:189)
at net.minecraft.client.renderer.BlockModelRenderer.func_187498_b(BlockModelRenderer.java:115)
at net.minecraftforge.client.model.pipeline.ForgeBlockModelRenderer.func_187498_b(ForgeBlockModelRenderer.java:89)
at net.minecraft.client.renderer.BlockModelRenderer.func_187493_a(BlockModelRenderer.java:78)
at net.minecraft.client.renderer.BlockModelRenderer.func_178267_a(BlockModelRenderer.java:57)
at net.minecraft.client.renderer.BlockRendererDispatcher.func_175018_a(BlockRendererDispatcher.java:80)
at net.minecraft.client.renderer.chunk.RenderChunk.func_178581_b(RenderChunk.java:328)
at net.minecraft.client.renderer.chunk.ChunkRenderWorker.func_178474_a(SourceFile:100)
at net.minecraft.client.renderer.chunk.ChunkRenderDispatcher.func_178505_b(ChunkRenderDispatcher.java:174)
at net.minecraft.client.renderer.RenderGlobal.func_174970_a(RenderGlobal.java:1482)
at net.minecraft.client.renderer.EntityRenderer.func_175068_a(EntityRenderer.java:1730)
at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1613)
at net.minecraft.client.renderer.EntityRenderer.func_181560_a(EntityRenderer.java:1384)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1118)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:397)
at net.minecraft.client.main.Main.main(SourceFile:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Thread: Client thread
Stacktrace:
at omtteam.openmodularturrets.blocks.BlockTurretBase.func_149751_l(BlockTurretBase.java:151)
at net.minecraft.block.state.BlockStateContainer$StateImplementation.func_185895_e(BlockStateContainer.java:327)
at net.minecraft.client.renderer.BlockModelRenderer$AmbientOcclusionFace.func_187491_a(BlockModelRenderer.java:660)
at net.minecraft.client.renderer.BlockModelRenderer.renderQuadsSmooth(BlockModelRenderer.java:189)
at net.minecraft.client.renderer.BlockModelRenderer.func_187498_b(BlockModelRenderer.java:115)
at net.minecraftforge.client.model.pipeline.ForgeBlockModelRenderer.func_187498_b(ForgeBlockModelRenderer.java:89)

-- Block model being tesselated --
Details:
Block: minecraft:leaves[check_decay=true,decayable=true,variant=oak]
Block location: World: (42,79,42), Chunk: (at 10,4,10 in 2,2; contains blocks 32,0,32 to 47,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Using AO: true
Stacktrace:
at net.minecraft.client.renderer.BlockModelRenderer.func_187493_a(BlockModelRenderer.java:78)
at net.minecraft.client.renderer.BlockModelRenderer.func_178267_a(BlockModelRenderer.java:57)

-- Block being tesselated --
Details:
Block type: ID #18 (tile.leaves // net.minecraft.block.BlockOldLeaf // minecraft:leaves)
Block data value: 8 / 0x8 / 0b1000
Block location: World: (42,79,42), Chunk: (at 10,4,10 in 2,2; contains blocks 32,0,32 to 47,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Stacktrace:
at net.minecraft.client.renderer.BlockRendererDispatcher.func_175018_a(BlockRendererDispatcher.java:80)
at net.minecraft.client.renderer.chunk.RenderChunk.func_178581_b(RenderChunk.java:328)
at net.minecraft.client.renderer.chunk.ChunkRenderWorker.func_178474_a(SourceFile:100)
at net.minecraft.client.renderer.chunk.ChunkRenderDispatcher.func_178505_b(ChunkRenderDispatcher.java:174)
at net.minecraft.client.renderer.RenderGlobal.func_174970_a(RenderGlobal.java:1482)
at net.minecraft.client.renderer.EntityRenderer.func_175068_a(EntityRenderer.java:1730)
at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1613)

-- Affected level --
Details:
Level name: MpServer
All players: 1 total; [EntityPlayerSP['demonseeker'/1026, l='MpServer', x=43.30, y=80.00, z=42.67]]
Chunk stats: MultiplayerChunkCache: 529, 529
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (40,64,40), Chunk: (at 8,4,8 in 2,2; contains blocks 32,0,32 to 47,255,47), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 1174 game time, 1174 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Forced entities: 71 total; [EntitySpider['Паук'/4159, l='MpServer', x=-30.50, y=28.00, z=36.50], EntityCow['Корова'/64, l='MpServer', x=-15.50, y=84.00, z=-1.50], EntityCow['Корова'/65, l='MpServer', x=-14.80, y=78.00, z=-5.51], EntityCow['Корова'/66, l='MpServer', x=-20.68, y=76.00, z=-4.70], EntityCow['Корова'/67, l='MpServer', x=-18.60, y=78.00, z=-3.45], EntityCow['Корова'/68, l='MpServer', x=-18.50, y=107.00, z=72.50], EntityCow['Корова'/69, l='MpServer', x=-18.50, y=108.00, z=73.50], EntityCow['Корова'/70, l='MpServer', x=-19.50, y=107.00, z=72.50], EntityCow['Корова'/71, l='MpServer', x=-15.81, y=114.00, z=78.47], EntityCow['Корова'/80, l='MpServer', x=17.50, y=109.00, z=86.50], EntityCow['Корова'/81, l='MpServer', x=15.50, y=110.00, z=86.55], EntityCow['Корова'/82, l='MpServer', x=15.50, y=110.00, z=85.59], EntityCow['Корова'/83, l='MpServer', x=16.50, y=109.00, z=83.50], EntityCow['Корова'/96, l='MpServer', x=47.50, y=80.00, z=95.50], EntityCow['Корова'/97, l='MpServer', x=48.50, y=80.00, z=95.50], EntityCow['Корова'/98, l='MpServer', x=47.50, y=80.00, z=98.50], EntityCow['Корова'/99, l='MpServer', x=44.50, y=80.00, z=94.50], EntityZombie['Зомби'/4197, l='MpServer', x=-29.50, y=28.00, z=36.50], EntityCow['Корова'/120, l='MpServer', x=76.50, y=72.00, z=3.50], EntityCow['Корова'/121, l='MpServer', x=77.50, y=72.00, z=3.50], EntityCow['Корова'/122, l='MpServer', x=77.50, y=71.00, z=5.50], EntityCow['Корова'/123, l='MpServer', x=73.50, y=70.00, z=6.50], EntityCreeper['Крипер'/4230, l='MpServer', x=-29.50, y=39.00, z=55.50], EntityZombie['Зомби'/4241, l='MpServer', x=-16.50, y=37.00, z=111.50], EntityPig['Свинья'/147, l='MpServer', x=105.50, y=87.00, z=-36.50], EntityPig['Свинья'/148, l='MpServer', x=110.49, y=94.00, z=-36.67], EntityCow['Корова'/150, l='MpServer', x=111.50, y=77.00, z=-28.50], EntityCow['Корова'/151, l='MpServer', x=110.50, y=81.00, z=-30.50], EntityCow['Корова'/152, l='MpServer', x=109.50, y=86.00, z=-32.50], EntityCow['Корова'/153, l='MpServer', x=107.50, y=90.00, z=-35.50], EntityZombie['Зомби'/4250, l='MpServer', x=-18.50, y=16.00, z=-25.50], EntityZombie['Зомби'/4256, l='MpServer', x=-22.25, y=28.00, z=37.50], EntitySheep['Овца'/163, l='MpServer', x=118.36, y=106.00, z=-17.34], EntityCreeper['Крипер'/4301, l='MpServer', x=-31.50, y=13.00, z=-29.50], EntityBat['Летучая мышь'/4302, l='MpServer', x=-33.55, y=43.05, z=63.37], EntityZombie['Зомби'/4309, l='MpServer', x=-21.50, y=15.00, z=-25.50], EntityZombie['Зомби'/4329, l='MpServer', x=-18.50, y=43.00, z=108.50], EntityCreeper['Крипер'/4335, l='MpServer', x=-19.50, y=47.00, z=21.50], EntityBat['Летучая мышь'/4351, l='MpServer', x=-17.47, y=22.26, z=31.92], EntityZombie['Зомби'/4376, l='MpServer', x=-27.50, y=14.00, z=-26.50], EntityBat['Летучая мышь'/4380, l='MpServer', x=-17.41, y=46.22, z=110.52], EntityEnderman['Эндермен'/4388, l='MpServer', x=-18.50, y=41.00, z=116.50], EntityBat['Летучая мышь'/4393, l='MpServer', x=-11.08, y=38.52, z=48.83], EntityZombie['Зомби'/4404, l='MpServer', x=-33.50, y=28.00, z=29.50], EntityCreeper['Крипер'/4426, l='MpServer', x=-20.50, y=41.00, z=120.50], EntityCreeper['Крипер'/4428, l='MpServer', x=-20.50, y=41.00, z=111.50], EntitySkeleton['Скелет'/4437, l='MpServer', x=-18.50, y=15.00, z=-22.50], EntityCreeper['Крипер'/4441, l='MpServer', x=-19.50, y=15.00, z=-24.50], EntityCreeper['Крипер'/4442, l='MpServer', x=-17.50, y=15.00, z=-23.50], EntityCreeper['Крипер'/4450, l='MpServer', x=-19.49, y=47.00, z=25.82], EntityCreeper['Крипер'/4455, l='MpServer', x=-24.50, y=26.00, z=120.50], EntityCreeper['Крипер'/4466, l='MpServer', x=-19.50, y=38.00, z=54.50], EntitySkeleton['Скелет'/4472, l='MpServer', x=-18.50, y=38.00, z=53.50], EntityZombie['Зомби'/4478, l='MpServer', x=-22.50, y=41.00, z=48.50], EntityZombie['Зомби'/4480, l='MpServer', x=-33.55, y=39.00, z=58.26], EntitySkeleton['Скелет'/4481, l='MpServer', x=-25.27, y=38.00, z=54.36], EntitySkeleton['Скелет'/4482, l='MpServer', x=-27.50, y=38.00, z=52.50], EntitySkeleton['Скелет'/4504, l='MpServer', x=-17.50, y=111.00, z=100.50], EntityZombie['Зомби'/4507, l='MpServer', x=-22.95, y=28.00, z=37.50], EntityZombie['Зомби'/4508, l='MpServer', x=-10.75, y=111.00, z=106.46], EntityZombie['Зомби'/4509, l='MpServer', x=-16.50, y=111.00, z=102.50], EntityBat['Летучая мышь'/4524, l='MpServer', x=-22.57, y=14.02, z=-28.20], EntityItem['item.tile.doublePlant.rose'/4525, l='MpServer', x=56.27, y=74.00, z=-7.39], EntityBat['Летучая мышь'/4538, l='MpServer', x=-16.66, y=28.53, z=115.53], EntityBat['Летучая мышь'/4540, l='MpServer', x=-8.64, y=25.08, z=120.95], EntitySkeleton['Скелет'/4560, l='MpServer', x=-24.50, y=40.00, z=121.50], EntityCreeper['Крипер'/4565, l='MpServer', x=-20.50, y=40.00, z=117.50], EntityCreeper['Крипер'/4576, l='MpServer', x=-22.50, y=40.00, z=119.50], EntityBat['Летучая мышь'/4582, l='MpServer', x=-20.63, y=16.04, z=-24.44], EntityBat['Летучая мышь'/4586, l='MpServer', x=-33.71, y=22.47, z=35.47], EntityPlayerSP['demonseeker'/1026, l='MpServer', x=43.30, y=80.00, z=42.67]]
Retry entities: 0 total; []
Server brand: fml,forge
Server type: Integrated singleplayer server
Stacktrace:
at net.minecraft.client.multiplayer.WorldClient.func_72914_a(WorldClient.java:532)
at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2740)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:418)
at net.minecraft.client.main.Main.main(SourceFile:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --
Details:
Minecraft Version: 1.12.2
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_161, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 329711912 bytes (314 MB) / 657629184 bytes (627 MB) up to 3207856128 bytes (3059 MB)
JVM Flags: 5 total; -Xmx3072M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
FML: MCP 9.42 Powered by Forge 14.23.5.2768 Optifine OptiFine_1.12.2_HD_U_E1 6 mods loaded, 6 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

| State     | ID                 | Version      | Source                                  | Signature                                |
|:--------- |:------------------ |:------------ |:--------------------------------------- |:---------------------------------------- |
| UCHIJAAAA | minecraft          | 1.12.2       | minecraft.jar                           | None                                     |
| UCHIJAAAA | mcp                | 9.42         | minecraft.jar                           | None                                     |
| UCHIJAAAA | FML                | 8.0.99.99    | forge-1.12.2-14.23.5.2768.jar           | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| UCHIJAAAA | forge              | 14.23.5.2768 | forge-1.12.2-14.23.5.2768.jar           | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| UCHIJAAAA | omlib              | 3.1.0-208    | omlib-1.12.2-3.1.0-208.jar              | None                                     |
| UCHIJAAAA | openmodularturrets | 3.1.0-306    | openmodularturrets-1.12.2-3.1.0-306.jar | None                                     |

Loaded coremods (and transformers): 
GL info: ' Vendor: 'NVIDIA Corporation' Version: '4.6.0 NVIDIA 398.82' Renderer: 'GeForce GTX 750/PCIe/SSE2'
Launched Version: ForgeOptiFine 1.12.2
LWJGL: 2.9.4
OpenGL: GeForce GTX 750/PCIe/SSE2 GL version 4.6.0 NVIDIA 398.82, NVIDIA Corporation
GL Caps: Using GL 1.3 multitexturing.

Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes
Is Modded: Definitely; Client brand changed to 'fml,forge'
Type: Client (map_client.txt)
Resource Packs: laacis2's Natural 2k+.zip
Current Language: Русский (Россия)
Profiler Position: N/A (disabled)
CPU: 6x Intel(R) Core(TM) i5-8600 CPU @ 3.10GHz
OptiFine Version: OptiFine_1.12.2_HD_U_E1
OptiFine Build: 20180628-111228
Render Distance Chunks: 12
Mipmaps: 0
Anisotropic Filtering: 1
Antialiasing: 0
Multitexture: false
Shaders: null
OpenGlVersion: 4.6.0 NVIDIA 398.82
OpenGlRenderer: GeForce GTX 750/PCIe/SSE2
OpenGlVendor: NVIDIA Corporation
CpuCount: 6

Can you try the dev builds? This build works fine on our test server and in my dev env.