Fix crash on dotplot/linear synteny import form and when closing linear synteny track

[cmdcolin]

Currently, there are a couple of crashes in synteny workflows

1. Closing a linear synteny track produces an error on getContainingView of displayModel
2. Opening a dotplot or linear synteny view in the import form without a PAF file specified produces a crash

[codecov]

Codecov Report

Merging #1871 (0cab769) into main (c384d5f) will decrease coverage by 0.02%.
The diff coverage is 7.69%.

@@            Coverage Diff             @@
##             main    #1871      +/-   ##
==========================================
- Coverage   58.56%   58.54%   -0.03%     
==========================================
  Files         460      460              
  Lines       21331    21335       +4     
  Branches     5090     5088       -2     
==========================================
- Hits        12493    12491       -2     
- Misses       8532     8538       +6     
  Partials      306      306              

Impacted Files	Coverage Δ
...tenyRenderer/components/LinearSyntenyRendering.tsx	1.63% <0.00%> (-0.06%)	⬇️
...ew/src/LinearSyntenyView/components/ImportForm.tsx	6.52% <0.00%> (ø)
...lot-view/src/DotplotView/components/ImportForm.tsx	78.04% <100.00%> (ø)
...inearGenomeView/components/RefNameAutocomplete.tsx	89.36% <0.00%> (-4.26%)	⬇️

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