`fly deploy -c nonexistent.file` doesn't fail

[ThisGuyCodes]

Describe the bug
When fly deploy is run with the --config flag set to a nonexistent file (and --app set to a valid fly app name), it continues to run the deploy anyway.

Technically I am requesting a breaking change; but this behavior is not intuitive, and caused hours of debugging for what ended up being something quite silly. I would be hard pressed to think of a situation where if I specified a config file that didn't exist I'd want it to continue.

• Operating system
• fly version

flyctl v0.3.123 darwin/arm64 Commit: 9651c39a645575cb00779649c804a4b823016e1c BuildDate: 2025-05-15T15:28:06Z

** Paste your fly.toml

Literally doesn't matter, or exist, that's the point

** Command output: **

Command operates normally.