Invalid header character with strange "equals" header in builtin node js http library

[iocmet]

Summary

When i tried send discord message with bot token that contains file i ran into this exception
throw new Error(error);
^

Error: TypeError [ERR_INVALID_CHAR]: Invalid character in header content ["equals"]
at Request._callback (/data/data/com.termux/files/home/Parser-Bot/node_modules/async-request/src/main.js:24:27)
at self.callback (/data/data/com.termux/files/home/Parser-Bot/node_modules/request/request.js:185:22)
at Request.emit (node:events:523:35)
at Request.start (/data/data/com.termux/files/home/Parser-Bot/node_modules/request/request.js:753:10)
at Request.write (/data/data/com.termux/files/home/Parser-Bot/node_modules/request/request.js:1491:10)
at FormData.ondata (node:internal/streams/legacy:20:31)
at FormData.emit (node:events:511:28)
at CombinedStream.write (/data/data/com.termux/files/home/Parser-Bot/node_modules/combined-stream/lib/combined_stream.js:138:8)
at CombinedStream._pipeNext (/data/data/com.termux/files/home/Parser-Bot/node_modules/combined-stream/lib/combined_stream.js:126:8)
at CombinedStream._realGetNext (/data/data/com.termux/files/home/Parser-Bot/node_modules/combined-stream/lib/combined_stream.js:99:10)

Simplest Example to Reproduce

Im not sure why it happening but you can try send discord message with file

Expected Behavior

POST request will just be send

Current Behavior

Invalid character in header content error

Possible Solution

I don't know

Context

Send discord message from bot account with file (maybe send POST with multipart/form-data type is more correct but i successfully do this using request before)

Your Environment

software	version
request	latest
node	20.2.0
npm	9.6.6
Operating System
Android armv8 (not matters at all i think)

[iocmet]

After recursive code commenting and running script i found that this line causes error (still looking for most low level reason)

[iocmet]

For some strange reason "equals" method is being added to headers, self.headers:

{
... other headers
equals: [Function: objectEquals]
}

[iocmet]

Root of problem is in caseless package and it happened because i declared equals method in Object prototype, you can access objects from prototype with for loop or like obj['protoValue']