fix missing class name in user relation

app/models/semester_process_mail.rb

 class SemesterProcessMail < ApplicationRecord
   belongs_to :semester_process_volunteer
-  belongs_to :sent_by, references: :users, class_name: 'User', inverse_of: 'semester_process_mails'
+  belongs_to :sent_by, class_name: 'User', inverse_of: 'semester_process_mails'
 
   enum kind: { mail: 0, reminder: 1 }
 

app/models/semester_process_volunteer.rb

@@ -8,7 +8,7 @@ class SemesterProcessVolunteer < ApplicationRecord
   belongs_to :commited_by, -> { with_deleted }, class_name: 'User',
     inverse_of: 'semester_processes', optional: true
 
-  has_many :semester_process_volunteer_missions, dependent: :destroy
+  has_many :semester_process_volunteer_mission, dependent: :destroy
   has_many :semester_feedbacks, dependent: :destroy
   has_many :hours, dependent: :nullify
 

app/models/user.rb

@@ -81,13 +81,15 @@ class User < ApplicationRecord
 
   # Semester Process relations
   #
-  has_many :semester_processes, inverse_of: 'creator', foreign_key: 'creator_id', dependent: :destroy
+  has_many :semester_processes, inverse_of: 'creator', foreign_key: 'creator_id',
+    class_name: 'SemesterProcess', dependent: :destroy
   has_many :semester_process_mails_posted, inverse_of: 'mail_posted_by',
-    foreign_key: 'mail_posted_by_id', dependent: :nullify
+    class_name: 'SemesterProcess', foreign_key: 'mail_posted_by_id', dependent: :nullify
   has_many :semester_process_reminder_mail_posted, inverse_of: 'reminder_mail_posted_by',
-    foreign_key: 'reminder_mail_posted_by_id', dependent: :nullify
+    class_name: 'SemesterProcess', foreign_key: 'reminder_mail_posted_by_id', dependent: :nullify
 
-  has_many :semester_process_mails, dependent: :nullify
+  has_many :semester_process_mails, class_name: 'SemesterProcessMail', foreign_key: 'sent_by_id',
+    inverse_of: 'sent_by', dependent: :nullify
   has_many :semester_process_reminders, -> { reminder }, through: :semester_process_mails
 
   has_many :semester_process_responsibilities, inverse_of: 'responsible',