Adds login ability, error handling, and logging (#1)

Reviewed-on: #1
Co-authored-by: aarbit <aarbit@gmail.com>
Co-committed-by: aarbit <aarbit@gmail.com>

src/main/kotlin/net/halfbinary/scavengerhuntapi/error/ExceptionHandler.kt

@@ -0,0 +1,31 @@
+package net.halfbinary.scavengerhuntapi.error
+
+import net.halfbinary.scavengerhuntapi.error.exception.InvalidEmailException
+import net.halfbinary.scavengerhuntapi.error.exception.LoginFailedException
+import net.halfbinary.scavengerhuntapi.error.exception.PreexistingAccountException
+import org.springframework.http.HttpStatus
+import org.springframework.web.bind.annotation.ExceptionHandler
+import org.springframework.web.bind.annotation.ResponseStatus
+import org.springframework.web.bind.annotation.RestControllerAdvice
+
+@RestControllerAdvice
+class ExceptionHandler {
+
+    @ExceptionHandler(PreexistingAccountException::class)
+    @ResponseStatus(HttpStatus.CONFLICT)
+    fun preexistingAccountException(e: PreexistingAccountException): String? {
+        return e.message
+    }
+
+    @ExceptionHandler(LoginFailedException::class)
+    @ResponseStatus(HttpStatus.UNAUTHORIZED)
+    fun loginFailedException(e: LoginFailedException): String? {
+        return e.message
+    }
+
+    @ExceptionHandler(InvalidEmailException::class)
+    @ResponseStatus(HttpStatus.BAD_REQUEST)
+    fun invalidEmailException(e: InvalidEmailException): String? {
+        return e.message
+    }
+}