showSnackBar error: showing snackbar before screen is built

[Ayush0Chaudhary]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce
Steps to reproduce the behavior:

1. Use this org url https://talawaapi.azurewebsites.net/graphql
2. click o sign up button
3. screen will appear

Expected behavior
Should provide with poper error

Actual behavior
giving this error screen

Screenshots

Additional details
I checked the error stack and it showed the this line showed this error

talawa/lib/services/database_mutation_functions.dart

Lines 126 to 128 in ac0571b

	// if the error is unknown
	navigationService.showSnackBar("Something went wrong");
	return false;

we have to make the changes in these line too so we don't get same error in the future

talawa/lib/services/database_mutation_functions.dart

Lines 89 to 124 in ac0571b

	if (exception.graphqlErrors[i].message == userNotFound.message) {
	if (showSnackBar) {
	navigationService
	.showSnackBar("No account registered with this email");
	}
	return false;
	}
	// if the error message is "Membership Request already exists"
	if (exception.graphqlErrors[i].message == memberRequestExist.message) {
	if (showSnackBar) {
	navigationService.showSnackBar("Membership request already exist");
	}
	return false;
	}
	// if the error message is "Invalid credentials"
	if (exception.graphqlErrors[i].message == wrongCredentials.message) {
	if (showSnackBar) {
	navigationService.showSnackBar("Enter a valid password");
	}
	return false;
	}
	// if the error message is "Organization not found"
	if (exception.graphqlErrors[i].message == organizationNotFound.message) {
	if (showSnackBar) {
	navigationService.showSnackBar("Organization Not Found");
	}
	return false;
	}
	// if the error message is "Email address already exists"
	if (exception.graphqlErrors[i].message == emailAccountPresent.message) {
	if (showSnackBar) {
	navigationService
	.showSnackBar("Account with this email already registered");
	}
	return false;
	}

Potential internship candidates
Please read this if you are planning to apply for a Palisadoes Foundation internship #359

[Ayush0Chaudhary]

@palisadoes @noman2002 @TheHazeEffect please take a look and assign me this, I have solved this problem before also.

[Ayush0Chaudhary]

I corrected it on my local Machine and showed this error.

[palisadoes]

@Ayush0Chaudhary are you using TalawaErrorWidget for this?

[Ayush0Chaudhary]

Yes @palisadoes, should I use something else??

[palisadoes]

1. No, it was recently created and I want to make sure we consider using it.
2. Depending on your experience with it, we may want to adjust the widget to be more flexible.
3. We have an issue Utilize TalawaErrorWidget Throughout App #1437 that's on hold pending a few more developer experiences.

Your feedback on its use could be integrated into the other issue.