• My "Instance fields / Name Prefix" is an underscore
• Variable name is _test
• Generated a read/write property using Alt+Insert

• Attempting to rename the variable with the prefix to a new variable with a prefix causes the errors and invalid code
• The error appears to happen when renaming without a prefix (_test => funtest, etc)

The issue is that it renames the property to the same name as the variable (and shows those two scary error messages.) This, of course, leads to a name collision for private _test as String and public property _Test() as string.

// Andrew