jq '' file.json
jq \ '' \ file.json
ShellCheck found an empty string used as a command name. This is never valid.
If the command is intended to do nothing, use
: instead. Otherwise, determine why an empty string ended up as a command name and fix it accordingly. In the example, each line was interpreted as a separate command due to missing line continuations.
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.