'-help filter=convolve' never resolve the promise

**Describe the bug**
`-help filter=convolve` never resolve the promise.

**To Reproduce**
```javascript
const ffmpeg = createFFmpeg();

await ffmpeg.load();

await ffmpeg.run("-hide_banner", "-help", 'filter=convolve');

console.log('done');
```

**Expected behavior**
resolve after this command finished

**Screenshots**

**Desktop (please complete the following information):**
- OS: macOS
- Browser: chrome
- Version 104

**Smartphone (please complete the following information):**
- Device: [e.g. iPhone6]
- OS: [e.g. iOS8.1]
- Browser [e.g. stock browser, safari]
- Version [e.g. 22]

**Additional context**

console output:
```
Filter convolve
Convolve first video stream with second video stream.
slice threading supported
Inputs:
#0: main (video)
#1: impulse (video)
Outputs:
#0: default (video)
convolve AVOptions:
planes ..FV...... set planes to convolve (from 0 to 15) (default 7)
impulse ..FV...... when to process impulses (from 0 to 1) (default all)
first 0 ..FV...... process only first impulse, ignore rest
all 1 ..FV...... process all impulses
noise ..FV...... set noise (from 0 to 1) (default 1e-07)

framesync AVOptions:
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat)
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame.
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame. endall 1 ..FV...... End both streams.
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame. endall 1 ..FV...... End both streams. pass 2 ..FV...... Pass through the main input.
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame. endall 1 ..FV...... End both streams. pass 2 ..FV...... Pass through the main input. shortest ..FV...... force termination when the shortest input terminates (default false)
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame. endall 1 ..FV...... End both streams. pass 2 ..FV...... Pass through the main input. shortest ..FV...... force termination when the shortest input terminates (default false) repeatlast ..FV...... extend last frame of secondary streams beyond EOF (default true)
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame. endall 1 ..FV...... End both streams. pass 2 ..FV...... Pass through the main input. shortest ..FV...... force termination when the shortest input terminates (default false) repeatlast ..FV...... extend last frame of secondary streams beyond EOF (default true)
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame. endall 1 ..FV...... End both streams. pass 2 ..FV...... Pass through the main input. shortest ..FV...... force termination when the shortest input terminates (default false) repeatlast ..FV...... extend last frame of secondary streams beyond EOF (default true)This filter has support for timeline through the 'enable' option.
framesync AVOptions: eof_action ..FV...... Action to take when encountering EOF from secondary input (from 0 to 2) (default repeat) repeat 0 ..FV...... Repeat the previous frame. endall 1 ..FV...... End both streams. pass 2 ..FV...... Pass through the main input. shortest ..FV...... force termination when the shortest input terminates (default false) repeatlast ..FV...... extend last frame of secondary streams beyond EOF (default true)This filter has support for timeline through the 'enable' option.FFMPEG_END
```