fix: improve error message when there are errors in bottender.config.js

[chentsulin]

When any syntax errors happen in bottender.config.js, it should show those errors instead of failing silently.

[codecov-io]

Codecov Report

Merging #611 into master will decrease coverage by 0.03%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #611      +/-   ##
==========================================
- Coverage   80.83%   80.79%   -0.04%     
==========================================
  Files          95       95              
  Lines        4268     4270       +2     
  Branches     1034     1046      +12     
==========================================
  Hits         3450     3450              
+ Misses        781      779       -2     
- Partials       37       41       +4

Impacted Files	Coverage Δ
packages/bottender/src/cli/index.ts	0% <0%> (ø)	⬆️
...ackages/bottender/src/shared/getBottenderConfig.ts	50% <0%> (-12.5%)	⬇️
packages/create-bottender-app/src/shared/log.ts	0% <0%> (ø)	⬆️

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