Description:
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Some combinations in the pattern string the MessageFormatter class completely fails returning null on object initialization and fails with bogus exception message on format().

Using the newest PECL module available.

intl
Internationalization support: enabled
version: PECL-3.0.0
ICU version: 55.1
ICU Data version: 55.1

Test script:
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$msg = new MessageFormatter( "de_DE", "This is a number - {0,number}." );
var_dump( $msg->format( [ 654.987 ] ) );
$msg = new MessageFormatter( "de_DE", "This is an integer - {0,number,integer}." );
var_dump( $msg->format( [ 654.987 ] ) );
$msg = new MessageFormatter( "de_DE", "This is a combined number - {0,number} , {0,number,integer}." );
var_dump( $msg ); // $msg = null -> Fatal error: Call to a member function format() on a non-object, calling getErrorCode() is impossible
if( $msg !== null ) var_dump( $msg->format( [ 654.987 ] ) ); // never dumps anything

var_dump( MessageFormatter::formatMessage( "de_DE", "{itemCount}", [ "itemCount" => 5 ] ) );
var_dump( MessageFormatter::formatMessage( "de_DE", "{itemCount, plural, one {item} other {items} }", [ "itemCount" => 5 ] ) );
var_dump( MessageFormatter::formatMessage( "de_DE", "{itemCount} {itemCount, plural, one {item} other {items} }", [ "itemCount" => 5 ] ) ); // FAILS: why ...?
var_dump( MessageFormatter::formatMessage( "de_DE", "{itemCount,number} {itemCount, plural, one {item} other {items} }", [ "itemCount" => 5 ] ) ); // doesn't fail

var_dump( MessageFormatter::formatMessage( "en_US", "this is an unlocalized string {0,date}.", [ time() ] ) );
var_dump( MessageFormatter::formatMessage( "en_US", "this is an unlocalized string {0,date}.", [ new DateTime( "now" ) ] ) );
var_dump( MessageFormatter::formatMessage( "en_US", "this is an already localized string Oct 9, 2015.", [ time() ] ) );
$m = new MessageFormatter( "en_US", "this is an already localized string Oct 9, 2015." );
$m->format( [ new DateTime( "now" ) ] ); // Catchable fatal error: Object of class DateTime could not be converted to string