Symptoms
When trying to enter play mode, I am receiving the error below:
error CS1612: Cannot modify a value type return value of `__'. Consider
storing it in a temporary variable.
Cause
The CS1612 error occurs because value types are copied on assignment. When you retrieve a value type from a property or indexer, you are getting a copy of the object, not a reference to the object itself. The copy that is returned is not stored by the property or indexer because they are actually methods, not storage locations (variables).
The error displayed in this example:
error CS1612: Cannot modify a value type return value of
`UnityEngine.Transform.position'. Consider storing it in a
temporary variable.
Resolution
The error CS1612 is solved by storing the copy into a variable that you declare before you can modify it.
More Information
https://msdn.microsoft.com/en-us/library/wydkhw2c.aspx