PatrickW:
Hey imtdb,I´m definitely not an expert on this topic,
but I´m currently working on a wireless connection as well.Thank´s to this forum I bought a different board because I had the same error message.
I used the ESP 8266-01 as well and now I use a NodeMcu board
https://www.amazon.de/gp/product/B01GCK3J40/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
I still have some issues as well, but at least I could do a Wifi scan already
what I could not even do with the ESP 01 module.At least no more error messages so far
Hope I could help a bit.
Greetings from Upper Bavaria
Patrick
You made a good choice with the NodeMCU board.
ESP-01 to Arduino is not beginner-friendly.
Here's a list of the modules I would have bought if knew then what I know now. 
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