Werk #19051: Custom graphs: Fix internal error if an operation could not be found

Component	User interface
Title	Custom graphs: Fix internal error if an operation could not be found
Date	Feb 9, 2026
Level	Trivial Change
Class	Bug Fix
Compatibility	Compatible - no manual interaction needed
Checkmk versions & editions	3.0.0b1 Not yet released Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT 2.5.0b1 Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT 2.4.0p22 Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

Custom graphs might have crashed with

Internal error: operator_name='+' operands=[...] ...

in certain scenarios.

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