Uncaught TypeError: Cannot use 'in' operator to search for 'length' in null

Hi to all.
When I try to send an email of a quote, the <textarea> does not replicate the content of the template selected above.
The javascript console says:
Uncaught TypeError: Cannot use ‘in’ operator to search for ‘length’ in null
at c (dependencies.min.js:1)
at Function.each (dependencies.min.js:1)
at inject_email_template (scripts.min.js:1)
at HTMLDocument. (4:293)
at j (dependencies.min.js:2)
at Object.fireWith [as resolveWith] (dependencies.min.js:2)
at Function.ready (dependencies.min.js:2)
at HTMLDocument.h (dependencies.min.js:1)
Could I have made a mistake in the template settings?
(sorry for my pedestrian english)

A post was merged into an existing topic: Email template for quotes is not working on 1.5.x