safeNum should warn that the value passed is invalid

[mrsarm]

The function safeNum used to check a number from environment variables does not prevent the process to start if the value is invalid, .e.g. passing '25x' return a NaN value, that depending of how the variable is used later, may cause the process to fail, or just to behave as if the value is undefined.

We should change that and make the process to fail, or at least to WARN in the logs about the value.

[meghna-khemka]

Upon testing again I can confirm that if I pass a string it is picking default value of 50 instead of NaN .I believe this is not expected? Can we get this fixed...