How to fix bugs in Morse alphabet code?

[dokipo]

The error is saying it tried to lookup "t" in a dictionary and failed. The line where this happened is:

plain_text += morse[current_element]

If you look at your code morse only appears in these lines:

morse = {}
        plain_text += morse[current_element]

morse doesn't have any items at all. That is why it crashes when trying to lookup "t".

You should review the code that involves "alphabet". I added a line to print the dictionary.

for key, value in translation_dict.items():
    alphabet[key] = key
    alphabet[value] = value
print(alphabet)

And I don't think "alphabet" contains what you think it does. A sample...

Output:
{'a': 'a', '.-': '.-', 'b': 'b', '-...': '-...', 'c': 'c', '-.-

What is "alphabet" supposed to be? Since it is used in "encode()" I suspect it should be a dictionary of Morse codes for all the letters and numbers. But you already have a dictionary for that; translation_dict. What you don't have is a reverse dictionary for looking up the letter for a Morse code.
So you have a translation dictionary "alphabet" that cannot do translation, and your try to do translation with a dictionary that is empty.

At first I replace

    alphabet[key] = value
    alphabet[value] = key

next I writed

plain_text += alphabet[val]

instead

plain_text += val

So now output is

-/..../../...//../...//..-./../.-./.../-//-/./.../-/../-./--.//..././-./-/./-./-.-././.-.-.-///
-/..../../...//../...//..-./../.-./.../-//-/./.../-/../-./--.//..././-./-/./-./-.-././.-.-.-///
-....-his is s.-.-.-cond -....-.-.-.-s-....-ing s.-.-.-n-....-.-.-.-nc.-.-.-.
-....-his is -....-hird -....-.-.-.-s-....-ing s.-.-.-n-....-.-.-.-nc.-.-.-.
-.-/.-//-...///

It is good basis, I see that first two lines and the last one are encoded correctly.
But there is some problem in decoding, some chars are encrypted correctly but most of sentence not...