Core/Misc: Fix static analysis issues

Fix some static analysis issues reported by Coverity

(cherry picked from commit 89c535cf2a)

Conflicts:
	src/server/game/Entities/Player/Player.cpp

src/server/shared/Debugging/Errors.h

@@ -49,4 +49,10 @@ namespace Trinity
 
 #define ASSERT WPAssert
 
+template <typename T> inline T* ASSERT_NOTNULL(T* pointer)
+{
+    ASSERT(pointer);
+    return pointer;
+}
+
 #endif