PyAPI: Add exceptions to stack push/pop

Raise exception when stack limits are reached.

source/blender/gpu/GPU_matrix.h

@@ -113,6 +113,16 @@ const float (*gpuGetNormalMatrixInverse(float m[3][3]))[3];
 void gpuBindMatrices(const Gwn_ShaderInterface*);
 bool gpuMatricesDirty(void); /* since last bind */
 
+
+/* Python API needs to be able to inspect the stack so errors raise exceptions instead of crashing. */
+#ifdef USE_GPU_PY_MATRIX_API
+int GPU_matrix_stack_level_get_model_view(void);
+int GPU_matrix_stack_level_get_projection(void);
+/* static assert ensures this doesn't change! */
+#define GPU_PY_MATRIX_STACK_LEN 31
+#endif  /* USE_GPU_PY_MATRIX_API */
+
+
 #ifdef __cplusplus
 }
 #endif