check passes a show message whose text is an expression; mxbuild rejects it (CE0117) #2199

Version: mxcli nightly-174-gb88dc5b9b (2026-11-10), Mendix 11.16.0.

Repro. Inside a microflow:

show message information (if $Posted < 0 then 'The carrier cannot be reached.' else 'Done.');

• mxcli check --references passes, and exec writes the microflow.
• mxcli docker check then fails:

[error] [CE0117] "Error(s) in expression." at Show message activity '{1}'

Expected. A Show message activity takes a text template, not an expression. One of these:

• check refuses the form, and points to show message '<template>' type <Type> with {1} parameters;
• or the expression is written as a template parameter ('{1}' with {1} = <expr>), which is what the error caption suggests was half done.

Workaround. Split into an if with one literal show message '…' type Information; per branch.

Found while building a "Check parcels now" button in a Mendix app.