Yaml check: Fail if there is a filler but no %s term provided

[matentzn]

Right now, this is allowed:

text: "hello %"
- var

Happens very very often with hand crafted patterns, and the error message happens waaaay too late in the process (at pattern compile time), and is not readable.

[dosumis]

Clarification needed - Is this for cases where you accidentally write % instead of %s ?

[matentzn]

yes