[fix] Validate multi-ticker pandas arguments

[hydrosquall]

Summary of Changes

• Addresses [developer experience] Argument Validation + Helpful Error Message #262 with a more informative error message and updated test fixture to catch this case
• Builds off the investigations started by @Kuhn92 in Fixed Bug: KeyError: <ticker> for batch query #258

Checklist

• Code follows the style guidelines of this project
• Added tests for new functionality
• Update HISTORY.rst with an entry summarizing your change
• Tag a project maintainer

[codecov]

Codecov Report

Merging #263 into master will increase coverage by 0.09%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #263      +/-   ##
==========================================
+ Coverage   96.64%   96.73%   +0.09%     
==========================================
  Files           4        5       +1     
  Lines         179      184       +5     
==========================================
+ Hits          173      178       +5     
  Misses          6        6

Impacted Files	Coverage Δ
tiingo/api.py	96.64% <100%> (-0.07%)	⬇️
tiingo/exceptions.py	100% <100%> (ø)

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[codecov]

Codecov Report

Merging #263 into master will increase coverage by 0.09%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #263      +/-   ##
==========================================
+ Coverage   96.64%   96.73%   +0.09%     
==========================================
  Files           4        5       +1     
  Lines         179      184       +5     
==========================================
+ Hits          173      178       +5     
  Misses          6        6

Impacted Files	Coverage Δ
tiingo/api.py	96.64% <100%> (-0.07%)	⬇️
tiingo/exceptions.py	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e39b975...03e7b53. Read the comment docs.

[Kuhno92]

This error message seems to be way more related to the actuall error. Good Job ;)

Nevertheless i would like to see a feature in the future to get all metrics from a list of tickers with a single api call.

Kind Regards
Kuhno92

[hydrosquall]

Hi @Kuhno92 ,

Thanks for chiming in. I'm going to merge this updated error message for now, and file an issue to consider adding this new method as a feature request. Would something like this code snippet work for your use case?