CG_CONTEXT_SHOW_BACKTRACE required?

I breakpoint in my code and tried to do a `visualize subview`

I get this:
```
error: error: Execution was interrupted, reason: step over.
The process has been returned to the state before expression evaluation.
2021-11-08 16:31:52.610210+0000 MyApp[68056:11076538] [Unknown process name] CGContextSaveGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
2021-11-08 16:31:52.610799+0000 MyApp[68056:11076538] [Unknown process name] CGContextSaveGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
2021-11-08 16:31:52.611133+0000 MyApp[68056:11076538] [Unknown process name] CGContextGetBaseCTM: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
2021-11-08 16:31:52.611304+0000 MyApp[68056:11076538] [Unknown process name] CGContextConcatCTM: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
2021-11-08 16:31:52.611415+0000 MyApp[68056:11076538] [Unknown process name] CGContextSetBaseCTM: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
2021-11-08 16:31:52.611527+0000 MyApp[68056:11076538] [Unknown process name] CGContextSaveGState: invalid context 0x0. If you want to see the backtrace, please set CG_CONTEXT_SHOW_BACKTRACE environmental variable.
error: error: Execution was interrupted, reason: step over.
The process has been returned to the state before expression evaluation.
Could not get image data.
error: error: Execution was interrupted, reason: step over.
The process has been returned to the state before expression evaluation.
error: error: Execution was interrupted, reason: step over.
The process has been returned to the state before expression evaluation.
error: error: Execution was interrupted, reason: step over.
The process has been returned to the state before expression evaluation.
```