Call to `magma_free` results in `ExpatError: syntax error: line 1, column 49`

[maxale]

Steps To Reproduce

Run

magma_free('SetClassGroupBounds("GRH");IntegralPoints(EllipticCurve([0, 2656615644, 0, 2352535559981844768, 1296]))')

Expected Behavior

It should produce a result or meaningful error.

Actual Behavior

It produces a cryptic error:

ExpatError: syntax error: line 1, column 49

Additional Information

No response

Environment

- **OS**: Ubuntu 22.04.4 LTS
- **Sage Version**: 10.4.rc2

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide

[fchapoton]

the server returns 504 Gateway Timeout for this request ; probably too large

[maxale]

Sage's magma_free interface should properly communicate that error to the caller.

[fchapoton]

Please make a pull request fixing that

[fchapoton]

@maxale please review the fix