Fixes #9.

Improved error detection for FieldDefinition and TransactionStatement.
When two statements of the same type weren't properly terminated only one was parsed.
Fixed a issue where two consecutive SELECT statements where considered a UNION.

Author: udan11

src/Components/FieldDefinition.php

@@ -241,6 +241,13 @@ public static function parse(Parser $parser, TokensList $list, array $options =
                     $state = 6;
                     ++$list->idx;
                     break;
+                } else {
+                    $parser->error(
+                        __('A comma or a closing bracket was expected.'),
+                        $token
+                    );
+                    $state = 0;
+                    break;
                 }
             }
         }

src/Parser.php

@@ -321,7 +321,6 @@ public function parse()
 
             /**
              * Last transaction.
-             *
              * @var TransactionStatement
              */
             $lastTransaction = null;
@@ -336,7 +335,7 @@ public function parse()
              * Whether a union is parsed or not.
              * @var bool $inUnion
              */
-            $inUnion = true;
+            $inUnion = false;
 
             /**
              * The index of the last token from the last statement.
@@ -436,7 +435,14 @@ public function parse()
                         $lastTransaction = $statement;
                         $this->statements[] = $statement;
                     } elseif ($statement->type === TransactionStatement::TYPE_END) {
-                        $lastTransaction->end = $statement;
+                        if ($lastTransaction === null) {
+                            $this->error(
+                                __('No transaction was previously started.'),
+                                $token
+                            );
+                        } else {
+                            $lastTransaction->end = $statement;
+                        }
                         $lastTransaction = null;
                     }
                     continue;

src/Statement.php

@@ -169,6 +169,16 @@ public function build()
      */
     public function parse(Parser $parser, TokensList $list)
     {
+        /**
+         * Whether the beginning of this statement was previously parsed.
+         *
+         * This is used to delimit statements that don't use the usual
+         * delimiters.
+         *
+         * @var bool
+         */
+        $parsedBeginning = false;
+
         // This may be corrected by the parser.
         $this->first = $list->idx;
 
@@ -236,6 +246,16 @@ public function parse(Parser $parser, TokensList $list)
             }
 
             if (!empty(Parser::$STATEMENT_PARSERS[$token->value])) {
+                if ($parsedBeginning) {
+                    // New statement has started. We let the parser construct a
+                    // new statement and parse that one
+                    $parser->error(
+                        __('A new statement was found, but no delimiter between them.'),
+                        $token
+                    );
+                    break;
+                }
+                $parsedBeginning = true;
                 if (!$parsedOptions) {
                     ++$list->idx; // Skipping keyword.
                     $this->options = OptionsArray::parse(