Why does pasting a command into the chat return an error?

Your command is too long to fit in the chat. The chat only supports up to 255 characters per command.

Pasting it into the chat, only the first 255 characters are recorded. This is what is pasted in:

/tellraw @a ["",{"text":"Co-op >","color":"aqua"},{"text":" [PIG","color":"light_purple"},{"text":"+++","color":"aqua"},{"text":"]","color":"light_purple"},{"text":" Technoblade","color":"light_purple"},{"text":": I have come down from the land of potato g

As you can see, it stops at the "g" at the very end. The g is the 255th character, and everything else doesn't make it in, including the closing brackets to finish the JSON text, resulting in an error when the system reaches the end of text when it expected closing quotes.

If you put the command into a command block, it runs just fine: