Filter Curve EQ will crash if there is an envelope point outside of the selection

[crsib]

Describe the bug
Filter Curve EQ will crash if there is an envelope point outside of the selection

To Reproduce
Steps to reproduce the behavior:

1. Get some audio
2. Use envelope tool, generate some points
3. Select audio with an envelope point outside of the selection
4. Apply Filter Curve EQ
5. Observe

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots
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Additional information (please complete the following information):

• OS: [e.g. Mac High Sierra, Ubuntu 18.04, Windows 10]
• Version [e.g. Audacity 2.5.1]
• (if relevant) Sound Device [e.g. Windows WASAPI, USB Sound card]

Additional context
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[petersampsonaudacity]

I do not see this crash on W10 with 3.3.0/3.0.4 alpha audacity-win-3.0.4-alpha-20210813+4058470-64bit

But the before and after does look odd (probably not correct)

Before EQ

After EQ

In particular the discontinuous envelope does not look right to me,