fix(#591): add missing gh cli precheck (#594)

Signed-off-by: Andy Augustin <[email protected]>

Author: AndreasAugustin

src/entrypoint.sh

@@ -27,6 +27,11 @@ if [[ -z "${HOME}" ]]; then
   exit 1
 fi
 
+if ! [ -x "$(command -v gh)" ]; then
+  err "github-cli gh is not installed. 'https://github.com/cli/cli'";
+  exit 1;
+fi
+
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