corrupted large config file

[tomdavidson]

Hello, I had a list of 36 profiles - added by hand - but there must have been a syntax issue:

$ assume-aws-role list                               
/home/tom/.nvm/versions/node/v7.2.0/lib/node_modules/assume-aws-role/bin/assume-aws-role.js:70                        
        var aliases = Object.keys(config);                                                                            
                             ^                                                                                        
                                                                                                                      
TypeError: Cannot convert undefined or null to object                                                                 
    at Function.keys (<anonymous>)                                                                                    
    at Object.<anonymous> (/home/tom/.nvm/versions/node/v7.2.0/lib/node_modules/assume-aws-role/bin/assume-aws-role.js:70:23)                                                                                                               
    at Module._compile (module.js:571:32)                                                                             
    at Object.Module._extensions..js (module.js:580:10)                                                               
    at Module.load (module.js:488:32)                                                                                 
    at tryModuleLoad (module.js:447:12)                                                                               
    at Function.Module._load (module.js:439:3)                                                                        
    at Module.runMain (module.js:605:10)                                                                              
    at run (bootstrap_node.js:420:7)                                                                                  
    at startup (bootstrap_node.js:139:9)                 

After which assume-aws-role wiped my file.

 cat ~/.assume-aws-role/config                           
Error: source does not appear to be markup.

If it is user error, why doesn't the config file have a json extension? Need a graceful exit that does not change the file if it can not be read.