Indentation is part of YAML
The YAML parser reports the line and column of invalid input. Formatting keeps comments. Convert to JSON reads the values, so comments and YAML-specific presentation are not part of that output. Inspect or minify the converted JSON in the JSON formatter.
A worked example
octopus: arms: 8 is a mapping inside another mapping. Replacing indentation with tabs can make it invalid.
Before you use the result
One document at a time is supported. Custom tags are not interpreted, and unsafe integers are rejected for JSON conversion rather than rounded. Cyclic aliases cannot become ordinary JSON.