ESLintBear: Show errors shown in stderr
ESLintBear: Show errors shown in stderr

In some cases, eslint fails. Because of this, the user can't see any
results, nor does the user see any warning that it failed. We now show
the stderr to the user as a WARNING.

Fixes https://github.com/coala-analyzer/coala-bears/issues/730

damngamerz/coala-bears,naveentata/coala-bears,Vamshi99/coala-bears,ankit01ojha/coala-bears,gs0510/coala-bears,ku3o/coala-bears,Shade5/coala-bears,dosarudaniel/coala-bears,seblat/coala-bears,naveentata/coala-bears,Asnelchristian/coala-bears,gs0510/coala-bears,LWJensen/coala-bears,kaustubhhiware/coala-bears,damngamerz/coala-bears,coala-analyzer/coala-bears,Vamshi99/coala-bears,refeed/coala-bears,Shade5/coala-bears,srisankethu/coala-bears,Asnelchristian/coala-bears,Asnelchristian/coala-bears,incorrectusername/coala-bears,ankit01ojha/coala-bears,ankit01ojha/coala-bears,dosarudaniel/coala-bears,yash-nisar/coala-bears,vijeth-aradhya/coala-bears,coala-analyzer/coala-bears,dosarudaniel/coala-bears,incorrectusername/coala-bears,Asnelchristian/coala-bears,naveentata/coala-bears,shreyans800755/coala-bears,meetmangukiya/coala-bears,horczech/coala-bears,seblat/coala-bears,meetmangukiya/coala-bears,srisankethu/coala-bears,SanketDG/coala-bears,refeed/coala-bears,sounak98/coala-bears,gs0510/coala-bears,Vamshi99/coala-bears,yash-nisar/coala-bears,seblat/coala-bears,meetmangukiya/coala-bears,Vamshi99/coala-bears,madhukar01/coala-bears,horczech/coala-bears,seblat/coala-bears,madhukar01/coala-bears,incorrectusername/coala-bears,SanketDG/coala-bears,yashtrivedi96/coala-bears,meetmangukiya/coala-bears,naveentata/coala-bears,arjunsinghy96/coala-bears,dosarudaniel/coala-bears,vijeth-aradhya/coala-bears,ku3o/coala-bears,damngamerz/coala-bears,srisankethu/coala-bears,yashtrivedi96/coala-bears,vijeth-aradhya/coala-bears,ku3o/coala-bears,Vamshi99/coala-bears,srisankethu/coala-bears,LWJensen/coala-bears,vijeth-aradhya/coala-bears,aptrishu/coala-bears,refeed/coala-bears,sounak98/coala-bears,incorrectusername/coala-bears,ku3o/coala-bears,shreyans800755/coala-bears,refeed/coala-bears,yash-nisar/coala-bears,Shade5/coala-bears,madhukar01/coala-bears,Asnelchristian/coala-bears,gs0510/coala-bears,ankit01ojha/coala-bears,Shade5/coala-bears,shreyans800755/coala-bears,shreyans800755/coala-bears,coala/coala-bears,horczech/coala-bears,coala-analyzer/coala-bears,gs0510/coala-bears,kaustubhhiware/coala-bears,horczech/coala-bears,ankit01ojha/coala-bears,refeed/coala-bears,Shade5/coala-bears,aptrishu/coala-bears,seblat/coala-bears,yashtrivedi96/coala-bears,madhukar01/coala-bears,ku3o/coala-bears,SanketDG/coala-bears,SanketDG/coala-bears,kaustubhhiware/coala-bears,horczech/coala-bears,incorrectusername/coala-bears,coala/coala-bears,kaustubhhiware/coala-bears,seblat/coala-bears,arjunsinghy96/coala-bears,coala-analyzer/coala-bears,gs0510/coala-bears,coala-analyzer/coala-bears,aptrishu/coala-bears,madhukar01/coala-bears,meetmangukiya/coala-bears,gs0510/coala-bears,sounak98/coala-bears,shreyans800755/coala-bears,naveentata/coala-bears,Vamshi99/coala-bears,yashtrivedi96/coala-bears,LWJensen/coala-bears,Shade5/coala-bears,vijeth-aradhya/coala-bears,vijeth-aradhya/coala-bears,vijeth-aradhya/coala-bears,madhukar01/coala-bears,srisankethu/coala-bears,coala/coala-bears,Vamshi99/coala-bears,SanketDG/coala-bears,naveentata/coala-bears,dosarudaniel/coala-bears,horczech/coala-bears,refeed/coala-bears,coala/coala-bears,incorrectusername/coala-bears,shreyans800755/coala-bears,yashtrivedi96/coala-bears,ku3o/coala-bears,sounak98/coala-bears,srisankethu/coala-bears,damngamerz/coala-bears,damngamerz/coala-bears,shreyans800755/coala-bears,damngamerz/coala-bears,dosarudaniel/coala-bears,damngamerz/coala-bears,Asnelchristian/coala-bears,damngamerz/coala-bears,yashtrivedi96/coala-bears,dosarudaniel/coala-bears,kaustubhhiware/coala-bears,seblat/coala-bears,arjunsinghy96/coala-bears,ankit01ojha/coala-bears,meetmangukiya/coala-bears,SanketDG/coala-bears,aptrishu/coala-bears,coala/coala-bears,refeed/coala-bears,srisankethu/coala-bears,Vamshi99/coala-bears,horczech/coala-bears,naveentata/coala-bears,yash-nisar/coala-bears,incorrectusername/coala-bears,LWJensen/coala-bears,yash-nisar/coala-bears,sounak98/coala-bears,ankit01ojha/coala-bears,yash-nisar/coala-bears,vijeth-aradhya/coala-bears,ku3o/coala-bears,arjunsinghy96/coala-bears,LWJensen/coala-bears,srisankethu/coala-bears,yashtrivedi96/coala-bears,dosarudaniel/coala-bears,aptrishu/coala-bears,Asnelchristian/coala-bears,Asnelchristian/coala-bears,yash-nisar/coala-bears,ankit01ojha/coala-bears,damngamerz/coala-bears,yashtrivedi96/coala-bears,yash-nisar/coala-bears,shreyans800755/coala-bears,kaustubhhiware/coala-bears,coala/coala-bears,arjunsinghy96/coala-bears,arjunsinghy96/coala-bears,sounak98/coala-bears,ankit01ojha/coala-bears,kaustubhhiware/coala-bears,sounak98/coala-bears,kaustubhhiware/coala-bears,horczech/coala-bears,refeed/coala-bears,shreyans800755/coala-bears,coala-analyzer/coala-bears,seblat/coala-bears,coala-analyzer/coala-bears,horczech/coala-bears,coala/coala-bears,naveentata/coala-bears,gs0510/coala-bears,coala-analyzer/coala-bears,coala/coala-bears,SanketDG/coala-bears,srisankethu/coala-bears,meetmangukiya/coala-bears,meetmangukiya/coala-bears,vijeth-aradhya/coala-bears,Shade5/coala-bears,refeed/coala-bears,arjunsinghy96/coala-bears,aptrishu/coala-bears,madhukar01/coala-bears,Vamshi99/coala-bears,incorrectusername/coala-bears,madhukar01/coala-bears,coala/coala-bears,SanketDG/coala-bears,gs0510/coala-bears,LWJensen/coala-bears,aptrishu/coala-bears,aptrishu/coala-bears,yash-nisar/coala-bears,naveentata/coala-bears,damngamerz/coala-bears,ku3o/coala-bears,ku3o/coala-bears,LWJensen/coala-bears,damngamerz/coala-bears,arjunsinghy96/coala-bears,incorrectusername/coala-bears,aptrishu/coala-bears,SanketDG/coala-bears,refeed/coala-bears,coala/coala-bears,aptrishu/coala-bears,horczech/coala-bears,LWJensen/coala-bears,coala/coala-bears,shreyans800755/coala-bears,arjunsinghy96/coala-bears,srisankethu/coala-bears,sounak98/coala-bears,sounak98/coala-bears,coala-analyzer/coala-bears,kaustubhhiware/coala-bears,Shade5/coala-bears,Shade5/coala-bears,madhukar01/coala-bears,aptrishu/coala-bears,yash-nisar/coala-bears,yashtrivedi96/coala-bears,horczech/coala-bears,yash-nisar/coala-bears,ankit01ojha/coala-bears,ankit01ojha/coala-bears,dosarudaniel/coala-bears,Asnelchristian/coala-bears,srisankethu/coala-bears,meetmangukiya/coala-bears,refeed/coala-bears,Vamshi99/coala-bears,Vamshi99/coala-bears,coala/coala-bears,LWJensen/coala-bears,shreyans800755/coala-bears