MATLAB "Error using X" runtime failure in CI

MATLAB threw a runtime error from inside a function call. The "Error using X" header names the function and the next line states the real reason: wrong type, wrong size, or an invalid value. This is a genuine code failure, not a setup issue.

What this error means

A -batch run stops with "Error using X" and a reason such as "Matrix dimensions must agree" or "Invalid argument", then a stack trace. Tests report the same as a failure.

MATLAB

Error using  *
Incorrect dimensions for matrix multiplication. Check that the number of columns
in the first matrix matches the number of rows in the second matrix.

Error in solve (line 8)
    y = A * x;

Common causes

Argument types or sizes are wrong

The values passed at runtime violate the function contract - mismatched matrix dimensions, wrong class, or an empty input.

Data differs on the runner

CI loads different fixtures or generates different inputs than your local session, exposing a shape assumption.

How to fix it

Read the reason line, not just the header

Look at the line under "Error using X" - it states the exact violation.
Print the sizes/classes of the inputs at the failing call.
Fix the shape or type mismatch, or validate inputs with validateattributes.

analyze.m

% guard the contract so failures are explicit
validateattributes(x, {'double'}, {'vector'});

Reproduce with the CI fixtures

Run the failing function against the same data CI uses so the mismatch reproduces locally.

How to prevent it

Validate inputs with validateattributes at function boundaries.
Use the same fixtures locally and in CI.
Add tests that assert on input shapes and types.