Runtime error on syntax file when bad pattern

Description of the problem or steps to reproduce

   1   filetype: nfo
   2   
   3   detect:
   4       filename: "^(nfo|gnu|bsd|nix|unx|osx|win|[aso])\\.|\\.(nfo|list)$)"
   5   
   6   rules:
   7       - type:
   8           start: "(^|\\s)##"
   9           end: "$"
  10           rules: []
  11       - comment:
  12           start: "(^|\\s)#[^#]?"
  13           end: "$"
  14           rules: []
  15       - constant.string:
  16           start: ">\\s"
  17           end: "$"
  18           rules: []

If i misslead the pattern by forgetting an ")" at end, i get a runtime panic, and it wont start.
This should be fix by caught the regex compiler and throwing a syntax error message to explain and make easy debuging.

Micro encountered an error: runtime error: invalid memory address or nil pointer dereference
runtime.errorString runtime error: invalid memory address or nil pointer dereference
runtime/panic.go:212 (0x5600a028f77e)
runtime/panic.go:211 (0x5600a028f5cd)
github.com/zyedidia/micro/v2/internal/buffer/buffer.go:615 (0x5600a07682fe)
github.com/zyedidia/micro/v2/internal/buffer/buffer.go:332 (0x5600a0764529)
github.com/zyedidia/micro/v2/internal/buffer/buffer.go:227 (0x5600a0763aff)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:190 (0x5600a07d777d)
github.com/zyedidia/micro/v2/cmd/micro/micro.go:299 (0x5600a07d8643)
runtime/proc.go:203 (0x5600a027b6d2)
runtime/asm_amd64.s:1373 (0x5600a02a9a81)

It should prompt the same as bellow (when missed backslash on a \s)

Error parsing syntax file perl: yaml: line 5: found unknown escape character

Press enter to continue

Specifications

Version: 2.0.6
Commit hash: 60846f54
Compiled on July 16, 2020
OS: Archlinux and Gentoo
Terminal: xfce4-terminal

Start at internal/buffer/buffer.go around lines 615, 332, and 227, then follow the syntax-file loading path from cmd/micro/micro.go. Reproduce the malformed regex in the issue and compare it with the existing YAML escape error behavior. Done means a bad pattern reports a syntax error and prompt instead of causing a nil-pointer panic.